1. Field of The Invention
This invention relates to potted fasteners for cellular panels. More particularly, it refers to molded insert fasteners for potting into a preformed hole in a honeycomb core structure.
2. Description of The Prior Art
The use of potted fasteners for securing attachments to cellular honeycomb panels is well known. U.S. Pat. No. 3,339,609 describes a multi-component unit mounted with a resin in a preformed hole. This unit requires a throw-away retainer cap for holding the insert fastener in the hole while the resin is being injected. U.S. Pat. No. 3,646,981 describes an insert fastener with helical exterior ribs. U.S. Pat. No. 3,709,733 describes an insert fastener with coarse external threads. This insert requires a bolt and washer to secure the insert in its hole prior to curing of the mounting resin.
U.S. Pat. No. 3,884,006 describes an insert with axially spaced non-grooved heads. Such an insert when tested with an Instron device exhibits shear load and individual panel pull out loads less than the fastener of the present invention in direct comparison tests. U.S. Pat. No. 3,964,531 describes an insert with a self-contained cutting head, but insufficient exterior surface area for bonding with epoxy resins.
Other references such as U.S. Pat. Nos. 3,564,798; 3,742,673 and 4,296,586 describe insert fasteners that are employed with holes penetrating the entire honeycomb structure and wherein a nut and bolt is employed.
While the heretofore described prior art insert fasteners all have anchoring properties in honeycomb panels, they suffer one or more limitations such as low pull out or turning resistance, high cost or time consuming mounting procedure. An insert fastener is needed which has high load resistance to pull out and turning, is easy to manufacture and can be quickly mounted in a honeycomb panel.